1. Field of the Invention
The invention relates to a decontamination apparatus for treating radioactive contaminated material. More particularly, the invention relates to an apparatus for treating or disposing of liquid waste. Most particularly the invention relates to containment of liquid waste in a tank or other container.
2. Discussion of the Related Art
The invention is an apparatus for the collection, transport and processing of waste water containing radioactive contaminants. The radioactive contaminants include micron size organic and inorganic particles including micron size particles or fines, such as dust, water treating resin, sludge, bacterial growth and any other material that may contaminate process water in and around a nuclear laboratory or plant. All these particles are referred to generically as radioactively contaminated material. This material may be soluble or somewhat soluble in water. More troublesome contaminants include small particles of insoluble radioactive material that have a relatively high surface area to weight ratio. Such contaminants are carried along in flowing waste water. They also easily adhere to surfaces, and settle out in corners, crevices and other low flow velocity sites.
Because of the hazards associated with radioactive contaminated waste water, it is often undesirable to dispose of it. Instead, the waste water is processed and recycled for reuse. Processing includes settling, filtering, demineralizing, sterilizing and the like.
One means for collecting waste water containing radioactive contaminants is a pump station. U.S. Pat. No. 5,307,389 to T. K. Meneely et al. discloses a pump station including a diaphragm pump in a cylindrical collection tank. The tank is used to collect waste water before passing it along to be demineralized, sterilized and reused.
Prior means for collecting waste water are also known for their propensity to collect and retain deposits of radioactive particles over time. Deposits occur in the bottom corners of the stainless steel collection tank and in downstream piping, particularly at joints, crevices and at rough surfaces. Depositing of radioactive particles is the primary cause of a gradual increase in radiation levels in a waste water system. This has the potential for contaminating an entire system over time. U.S. Pat. No. 4,844,276 to Kunze et al. discloses a vessel for receiving an aqueous suspension containing radioactive solids. Another waste water sump has a vertically oriented 30-gallon stainless steel drum. The vertical drum walls were not filleted to the drum bottom, nor were contact surfaces polished.
There is a need in the art for a pump station for radioactive contaminated waste water, which is not susceptible to the deposition of radioactive particles.
The invention is a pump station for transferring radioactive particle-containing waste water. The pump station includes an enclosed sump and a pump. The enclosed sump has a vertically elongated, generally frusto conical interior surface and a bottom surface. The pump is a submersible volute centrifugal pump. The volute has a volute exterior surface and a volute inlet providing entry to an impeller that rotates in the horizontal plane. The volute exterior surface, the sump interior surface and the bottom surface are all made of stainless steel having a 30 Ra or finer finish.